The goal of this project is to compare the efficacy of two interventions for improving spoken language and reducing symptoms of autism: (1) Discrete trial training (DTT)--an applied behavior analysis approach emphasizing highly structured teaching of school readiness skills (match-to-sample, imitation, functional play, and receptive and expressive language) and (2) Interpersonal developmental approach (IDA): a visually supported, child-focused, flexible engagement, social communicative engagement approach on joint attention, symbolic play, and the use of conventional symbols within socially valid communicative contexts.